<HTML><HEAD><TITLE>ord_union(+Set1, +Set2, -Union, -New)</TITLE>
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<H1>ord_union(+Set1, +Set2, -Union, -New)</H1>
Computes the union and difference of Set2 and Set1
<DL>
<DT><EM>Set1</EM></DT>
<DD>A set
</DD>
<DT><EM>Set2</EM></DT>
<DD>A set
</DD>
<DT><EM>Union</EM></DT>
<DD>A set or variable
</DD>
<DT><EM>New</EM></DT>
<DD>A set or variable
</DD>
</DL>
<H2>Description</H2>
	Succeeds when Union is the union of Set1 and Set2, and New is the
	set of elements that are in Set2 but not in Set1.  This is useful
	in order to know which elements were newly added when incrementally
	merging sets.
    
<H3>Modes and Determinism</H3><UL>
<LI>ord_union(+, +, -, -) is det
</UL>
<H2>See Also</H2>
<A HREF="../../lib/ordset/ord_disjoint_union-3.html">ord_disjoint_union / 3</A>, <A HREF="../../lib/ordset/ord_union-3.html">ord_union / 3</A>, <A HREF="../../lib/ordset/ord_union-2.html">ord_union / 2</A>
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